Survey of motivation to participate in a birth cohort

（出生コホート参加へのモチベーションに

関する研究）

千葉大学大学院医学薬学府

環境健康科学専攻

（主任：羽田 明 教授）

山本 緑

1

ABSTRACT

For longitudinal prospective cohort studies to be successful, participants’ motivation

to provide information must be maintained. The aim of this study was to identify factors

that influence motivation to participate in a birth cohort, with a focus on the participants’

understanding of the study and their concerns about potential risks and burdens.

Questionnaires were mailed to 4,541 mothers and expectant mothers who participate in

a nationwide birth cohort study from which 2,387 responses (52.6%) were received. The

primary motivations for participation in the study were benefits to the participants’

children, monetary compensation, and contributing to making a better environment.

More than 30% of the respondents felt they lacked understanding of the study purpose

and requirements for participation. Fourteen percent were concerned about leakage of

personal information and 13% felt burdened by a long-term commitment to the study.

Respondents who had low initial motivation and/or were motivated by money or gifts

(goods) tended to have a poorer understanding of the study and more concerns about its

risks and burdens. To address these issues, more information about the study should be

provided in an easy-to-understand manner not only at the initial explanation for

informed consent, but also during the follow-up period.

2

INTRODUCTION

To address the influence of unfavorable environmental exposure on children’s

health,1,2 large-scale birth cohort studies have been conducted in a number of countries.3

In Japan, the Japan Environment and Children’s Study (JECS), a nationwide

government-funded birth cohort study, began in January 2011 with the objective of

evaluating the impact of environmental factors on children’s health and development.4,5

The predetermined recruitment goal of 100,000 pregnant women was achieved in March

2014 through the cooperative efforts of 15 medical university-based regional centers.

The default follow-up setting was to continue monitoring the participating children until

they reached age 13 years. In this birth cohort, mainly healthy pregnant women were

recruited, and participants were asked to provide biological samples and information

about their living environment, lifestyle, and health as well as their child’s development

over time.

The success of longitudinal cohort studies largely depends on whether a sufficient

number of participants can be recruited and whether their motivation to provide

information can be maintained over the course of the study. To that end, it is important

to understand the tendencies of participants and the factors that influence their

motivation. The tendencies of participants in birth cohort studies and clinical research

on newborn infants have been previously reported.6-11 Some studies examining

tendencies in hypothetical settings found that the willingness to participate depended

greatly on maternal characteristics7 and degree of risk.9 In an actual setting, Brumatti et

al. found that major reasons to participate in a newborn cohort study were contributing

to the research as well as willingness to benefit future mothers and children.10 Most of

the participants in that study also expressed trust in the host institutions. Daniels et al.

3

reported that many participants were motivated not only by making potential

contributions to science, but also by receiving information about their pregnancy.11 On

the other hand, a lack of understanding of the research12-16 and concerns about leakage

of personal information17-19 have been noted in a number of cohort and genomic studies.

Here, we hypothesized that a lack of understanding and concerns about the JECS

may result in low motivation to participate. To address this issue and identify factors

that could promote the success of longitudinal prospective cohort studies, we analyzed

the tendencies of participants in a large birth cohort. To our knowledge, this is the first

investigation of this kind.

4

MATERIALS AND METHODS

The Japan Environment and Children’s Study

The JECS is a birth cohort study conducted to evaluate the impact of various

environmental and genetic factors on the health of children up to 13 years of age. A total

of 103,106 pregnant women were enrolled in the study. Recruitment was conducted at

15 regional centers nationwide from January 2011 to May 2014. These regional centers

conducted recruitment in cooperation with maternity hospitals and local health centers.

Biological samples (mother’s blood, urine, hair, and breast milk, cord blood, and baby’s

dried blood spots and hair) and medical records continue to be collected, and

information about lifestyle, living environment, and child development is gathered

periodically by questionnaire. Portions of the biological samples are stored for genetic

analysis, and the plans are being designed to convert the biological sample repository

into a biobank for further scientific research.

The Center of Chiba Unit is one of the regional units carrying out the study and it

covers a total of 14 cities and towns in Chiba Prefecture, Japan. Recruitment was

conducted in consecutive steps: (1) a face-to-face explanation with accompanying

briefing materials by trained recruiters; (2) delivery of an explanatory booklet; and (3)

receipt of a signed consent form (on the same day or within several days). If prospective

participants wanted additional information, it was provided by telephone, e-mail, or the

study website. As a prerequisite for enrollment, participants were required to have basic

literacy so that they could complete the periodic questionnaires.

5

Questionnaire survey

The questionnaire used in this study was designed to ascertain the following: 1) the

participants’ initial motivation to participate, 2) the items for which they felt they had

insufficient understanding, and 3) their concerns. Respondents were classified according

to the type and level of their motivation, and then the level of understanding and/or

concern was compared between the groups.

For this study, anonymous questionnaires were mailed to 4,541 mothers and

expectant mothers who were participating in the JECS at the Center of Chiba Unit on

August 28th, 2013; 2,387 responses had been collected by April 30th, 2014 (response

rate, 52.6%). The questionnaire items are shown in Supplementary file S1. Categorical

data on the age of mothers, month and year of delivery, and residential area were also

collected, and a query regarding whether their participation was voluntary was included.

Motivation for participation (11 items, Figure 1), self-reported understanding of the

study (21 items, Figure 2), and concerns about the study (5 items, Figure 3) at the time

of enrollment were measured using a 3-point Likert scale. Two motivation items that

were found not to be applicable to all participants were excluded from the analysis.

This study was approved by the Research Ethics Committee of the Graduate School

of Medicine, Chiba University.

6

Data Analysis

The relationships between motivation and understanding and concerns were

examined using data from 2,106 returned questionnaires with complete answers for age,

motivation, understanding, and concerns. Maximum likelihood factor analyses (promax

rotation with Kaiser normalization) were conducted on 11 items for motivation, 21

items for understanding, and 5 items for concerns, and items with factor loadings ≥0.35

were summarized in four, six, and two factors, respectively. All factors were named in

reference to the factor loadings of each item. Factor scores were calculated for each

respondent on each factor. To classify the respondents based on their motivation, cluster

analysis of standardized factor scores for each motivation factor was performed using

Ward’s linkage to conceptualize cluster locations and squared Euclidean distance to

measure distances between respondents and clusters; this yielded four groups. Group

comparisons were conducted for continuous and categorical variables using the

Mann-Whitney U test and chi-square test with Bonferroni correction, respectively. A

p-value < 0.05 was considered statistically significant. Data analysis was performed

using SPSS statistics ver. 22 (IBM corporation, Armonk, NY).

7

RESULTS

Among the 4,541 mothers and expectant mothers who received the questionnaire,

responses were received from 2,387 (response rate, 52.6%). Respondents were more

representative of mothers in their 30s and 40s and those who had recently given birth

than other JECS participant groups (Table 1).

Motivation, understanding, and concerns of respondents

Figure 1 shows a list of motivation factors and levels of respondents’ motivation to

participate in the JECS at the Chiba unit. The most frequent motivation factor at the

time of enrollment was “benefit my children or grandchildren”, followed by “monetary

compensation” and “contributing to making a better environment”. Less than half of the

respondents considered the credibility of the research institute or the fact that it was a

national research study to be a motivating factor.

Figure 2 shows the level of the respondents’ self-rated understanding about

information to be disclosed before their decision to participate. Ninety percent of

respondents answered that they had a good understanding of the voluntary nature of

participation. Regarding confidentiality of personal information, requirements for

participation, study duration, and the purpose, 59–69% of respondents understood the

study well, which rose to more than 90% when including respondents who partially

understood. Concerning study procedures such as obtaining assent from their child in

the future, how medical records would be accessed, and the use of data collected, less

than half of the respondents understood well, which rose to 68–85% when including

respondents who partially understood.

Figure 3 shows the level of respondents’ concerns about the study at the time of

8

enrollment. About 14% and 13% of the respondents were concerned about leakage of

personal information and the burden of a long-term commitment to the study,

respectively. Significantly more participants concerned about leakage of personal

information were unclear whether their name would be disclosed to anyone other than

the institutions involved in the JECS compared with those who were less concerned or

not concerned at all (14% vs. 8%, respectively) (p<0.001).

Factor analyses and classification of respondents

Results of factor analyses identified four motivation factors, six understanding

factors, and two concern factors. The factor loadings are shown in Supplementary tables

S1–S3. From the factor loadings obtained, the motivation factors were named 1)

credibility, 2) helpful information, 3) money or gifts, and 4) contribution. The

understanding factors were named 1) implementation of the study, 2) handling of

personal data, 3) voluntary nature of participation, 4) outline of the study, 5) contact

information (including withdrawal procedure), and 6) analysis of data. The concern

factors were 1) risks and benefits and 2) mental burden. The cumulative contribution

ratios before rotation were 54.1% for the four motivation factors, 53.1% for the six

understanding factors, and 41.8% for the two concern factors.

Respondents were classified into four groups based on cluster analysis using

standardized motivation factor scores for each item. A comparison of standardized

motivation factor scores between the four groups is shown in Figure 4. Based on the

results, the groups were named 1) high overall motivation, 2) not motivated by money

or gifts, 3) motivated by money or gifts, and 4) low overall motivation.

9

Group comparisons of age, understanding, and concerns

A comparison of age, scores for the six understanding factors, and scores for the two

concern factors between group 1 (high overall motivation) and the other three groups is

shown in Table 2. The largest number of respondents were categorized into group 3

(motivated by money or gifts), followed by group 1 (high overall motivation).

Factor scores for understanding, except for “voluntary nature of participation”, were

highest in group 1 (high overall motivation), followed by group 2 (not motivated by

money or gifts), group 3 (motivated by money or gifts), and group 4 (low overall

motivation). Meanwhile, factor scores for concern increased in the reverse order.

Respondents in group 2 (not motivated by money or gifts) were significantly older than

those in group 1 (high overall motivation). More than 90% of the respondents in every

group answered that they made the decision to participate in the study on their own.

10

DISCUSSION

In this study, a substantial number of participants were found to have low overall

motivation or to be motivated by money or gifts. These respondents tended to have

more concerns and a poorer understanding of the cohort study than the other

respondents. This may indicate that these types of participants are at an increased risk of

dropping out from this long-term cohort study. If this is in fact the case, appropriate

measures need to be taken to maintain their commitment and motivation to continue,

such as providing addition explanations of the study content to deal with their level of

understanding and concerns.

Comprehending fully the content of a study and the measures that will be taken to

protect personal information through the initial informed consent procedures is almost

impossible for participants.12-16,20-22 In fact, in our cohort, only 59% of the respondents

felt that they had sufficient understanding of the purpose of the study, and even fewer

felt that they had enough information on data collection methods, the data that would be

analyzed, assent from their child in the future, and other study procedures. To improve

participants’ understanding of the study, more information about the study should be

provided in an easy-to-understand manner not only at the initial explanation for

informed consent, but also periodically throughout the duration of the study.

Although most of the participants were not concerned about the study content or

procedures, 14% were concerned about the risk of personal information leakage, and

13% were concerned about the burden of a long-term commitment. A previous study

showed that some people showed willingness to participate in a hypothetical biobank

while being concerned about privacy.18 In our study, there were significantly more

respondents who did not know whether their name would be disclosed to anyone other

11

than participating institutes in the group with concerns about privacy protection

compared with those with no or less concern. This result indicates that a limited

understanding about privacy protection may increase participants’ concerns. To address

this issue, more explanations about privacy protection and data management should be

provided.

In this study, we identified major motivating factors for participation in a large-scale

birth cohort study. We found that many respondents had self-interest motivations (e.g.,

benefit my children or grandchildren, monetary compensation, individual test results,

and helpful information about childrearing) as well as altruistic motivation factors (e.g.,

contributing to making a better environment). Previous studies also reported that most

participants of birth cohort surveys had altruistic motivation.10,11 Although altruism is a

principal factor in participation, it would be difficult to maintain participants’

willingness to take part in a long-term study based on altruistic motivation alone. A

review reported a decreased tendency of volunteerism as a factor in recent

uncooperativeness in epidemiologic studies with little immediate benefit to participants

themselves.23 Offering incentives to serve participants’ self-interests may improve their

disposition. Given that studies found that participants expected their individual data to

be returned and that this was one of their key motivating factors for participating in a

study, highlighting the return of individual test results could be an effective strategy for

encouraging long-term participation.24,25 The effect of monetary compensation on

encouraging participation has, however, been inconsistent among studies.8,17,25-27 In our

study, although monetary compensation seemed to be a major motivating factor, it is a

difficult strategy to employ due to financial limitations and potential ethical concerns.28

Unexpectedly, compared with an Italian hospital-based birth cohort in which 78% of

the participants cited the credibility of the research institute as the reason for their

12

participation,10 in our study this was a relatively minor factor. Similarly, another study

found that the credibility of the research institution was low in terms of motivation to

participate in a Japanese population-based genomic epidemiological study.29 The

discrepancy could be due to differences in study design—whether the study is hospital-

or population-based—and/or cultural differences.

Our study has several limitations. First, we assumed that a lack of understanding and

numerous concerns would cause low levels of motivation; however, due to the nature of

the cross-sectional study design, the opposite causal relationship cannot be excluded. It

is possible that participants did not try to understand and had numerous concerns

because of their low overall motivation to participate. Second, to avoid false

descriptions due to participants worrying that their answers would be identifiable to

researchers, this survey was conducted anonymously. Therefore, it was not possible to

investigate whether the group with weak overall motivation actually had a tendency to

drop out. Further study is required to address this issue. Third, information about social

and educational situations was not available in this survey. Younger JECS participants

tend to have lower household income and lower educational attainment. In this study,

the group that was not motivated by monetary compensation had a larger number of

older participants than younger ones, which may be associated with their higher

household income and educational attainment. Finally, this survey was conducted with

participants who enrolled in the Center of Chiba Unit and it is unclear whether the

results would apply to all participants of the JECS. The participants in the Chiba unit are

estimated to cover about 40% of all pregnant women in the research area, which is

comparable to estimates in the other JECS units (47%).

In conclusion, we found for the first time that participants with low overall

motivation and participants motivated by money or gifts alone had limited

13

understanding and numerous concerns about the study. These results suggest a need to

address these issues by providing further explanations about the study not only at the

time of enrollment, but also periodically throughout the duration of the study.

14

ACKNOWLEDGMENTS

This study was supported in part by a grant for the Japan Environment & Children's

Study from the Ministry of the Environment, Japan.

This research was supported by JSPS KAKENHI Grant Number 23590587.

We thank the study participants and the officers and staff of the participating institutions

in the Center of Chiba Unit of the Japan Environment and Children’s Study.

Notes: The findings and conclusions of this article are solely the responsibility of the

authors and do not represent the official views of the Japanese government.

The authors declare that they have no competing interests.

Supplementary tables S1 – S3 and Supplementary file S1 containing the feedback

questionnaire form are available at the website of the Journal of Human Genetics:

http://www.nature.com/jhg/index.html?WT.mc_id=SPG_JHG_society.

15

REFERENCES

1 Landrigan, P. J., Kimmel, C. A., Correa, A. & Eskenazi, B. Children's health and the

environment: public health issues and challenges for risk assessment. Environ.

Health Perspect. 112, 257-265 (2004).

2 Prüss-Üstün, A. & Corvalán, C. Preventing disease through healthy environments.

Towards an estimate of the environmental burden of disease. WHO (World Health

Organization) Library Cataloguing-in-Publication Data (2006).

http://www.who.int/quantifying_ehimpacts/publications/preventingdisease.pdf

Accessed 22 November 2015.

3 Lawlor, D. A., Andersen, A. M. & Batty, G. D. Birth cohort studies: past, present

and future. Int. J. Epidemiol. 38, 897-902 (2009).

4 Kawamoto, T., Nitta, H., Murata, K., Toda, E., Tsukamoto, N. & Hasegawa, M.

Rationale and study design of the Japan environment and children’s study (JECS).

BMC Public Health 14, 25-32 (2014).

5 Michikawa, T., Nitta, H., Nakayama, S. F., Ono, M., Yonemoto, J., Tamura, K. et al.

The Japan Environment and Children's Study (JECS): A Preliminary Report on

Selected Characteristics of Approximately 10 000 Pregnant Women Recruited

During the First Year of the Study. J. Epidemiol. 25, 452-458 (2015).

6 Nechuta, S., Mudd, L. M., Biery, L., Elliott, M.R., Lepkowski, J. M., Paneth, N. et

al. Attitudes of pregnant women towards participation in perinatal epidemiological

research. Paediatr. Perinat. Epidemiol. 23, 424-430 (2009).

7 Nechuta, S., Mudd, L. M., Elliott, M. R., Lepkowski, J. M., Paneth, N. & Michigan

Alliance for the National Children's Study. Attitudes of pregnant women towards

collection of biological specimens during pregnancy and at birth. Paediatr. Perinat.

Epidemiol. 26, 272-275 (2012).

8 Qiu, X., He, J., Qiu, L., Larson, C. P., Xia, H. & Lam, K. B. Willingness of pregnant

women to participate in a birth cohort study in China. Int. J. Gynaecol. Obstet. 122,

216-218 (2013).

9 Maayan-Metzger, A., Kedem-Friedrich, P. & Kuint, J. Motivations of mothers to

enroll their newborn infants in general clinical research on well-infant care and

development. Pediatrics 121, e590-596. doi: 10.1542/peds.2007-1571 (2008).

16

10 Brumatti, L. V., Montico, M., Russian, S., Tognin, V., Bin, M., Barbone, F., Volpi,

P. & Ronfani, L. Analysis of motivations that lead women to participate (or not) in a

newborn cohort study. BMC Pediatrics 13, 53 (2013).

11 Daniels, J. L., Savitz, D. A., Bradley, C., Dole, N., Evenson, K. R., Eucker, B. et al.

Attitudes toward participation in a pregnancy and child cohort study. Paediatr.

Perinat. Epidemiol. 20, 260-266 (2006).

12 Helgesson, G., Ludvigsson, J. & Stolt, U. G. How to handle informed consent in

longitudinal studies when participants have a limited understanding of the study. J.

Med. Ethics 31, 670-673 (2005).

13 Stolt, U. G., Helgesson, G., Liss, P. E., Svensson, T. & Ludvigsson, J. Information

and informed consent in a longitudinal screening involving children: a questionnaire

survey. Eur. J. Hum. Genet. 13, 376-383 (2005).

14 McCarty, C. A., Nair, A., Austin, D. M. & Giampietro, P. F. Informed consent and

subject motivation to participate in a large, population-based genomics study: the

Marshfield clinic personalized medicine research project. Community Genet. 10, 2-9

(2007).

15 Matsui, K., Lie, R. K., Turin, T. C. & Kita, Y. A randomized controlled trial of short

and standard-length consent formes for a genetic cohort study: Is longer better? J.

Epidemiol. 22, 308-316 (2012).

16 Robinson, J. O., Slashinski, M. J., Wang, T., Hilsenbeck, S. G. & McGuire, A. L.

Participants' recall and understanding of genomic research and large-scale data

sharing. J. Empir. Res. Hum. Res. Ethics 8, 42-52 (2013).

17 Kaufman, D. J., Murphy-Bollinger, J., Scott, J. & Hudson, K. L. Public opinion

about the importance of privacy in biobank research. Am. J. Hum. Genet. 85,

643–654 (2009).

18 Kerath, S. M., Klein, G., Kern, M., Shapira, I., Witthuhn, J., Norohna, N. et al.

Beliefs and attitudes towards participating in genetic research - a population based

cross-sectional study. BMC Public Health. 13, 114 (2013).

19 Lakes, K. D., Vaughan, E., Jones, M., Burke, W., Baker, D. & Swanson, J. M.

Diverse perceptions of the informed consent process: implications for the

recruitment and participation of diverse communities in the National Children's

Study. Am. J. Community Psychol. 49, 215-232 (2012).

17

20 O'Neill, O. Autonomy and trust in bioethics. (Cambridge University Press, New

York, NY, USA, 2002).

21 Hansson, M. G. Building on relationships of trust in biobank research. J. Med.

Ethics 31, 415–418 (2005).

22 Allen, J. & McNamara, B. Reconsidering the value of consent in biobank research.

Bioethics 25, 155-166 (2011).

23 Galea, S. & Tracy, M. Participation rates in epidemiologic studies. Ann. Epidemiol.

17, 643-653 (2007).

24 Harris, E. D., Ziniel, S. I., Amatruda, J. G., Clinton, C. M., Savage, S. K., Taylor, P.

L. et al. The beliefs, motivations, and expectations of parents who have enrolled

their children in a genetic biorepository. Genet. Med. 14, 330-337 (2012).

25 Kaufman D, Murphy J, Scott J, Hudson K. Subjects matter: a survey of public

opinions about a large genetic cohort study. Genet. Med. 10, 831–839 (2008).

26 Jenkins, M. M., Reed-Gross, E., Barfield, W. D., Prue, C. E., Gallagher, M. L.,

Rasmussen, S. A. et al. Qualitative assessment of study materials and

communication strategies used in studies that include DNA collection. Am. J. Med.

Genet. A. 155A, 2721-2731 (2011).

27 Glidewell, J., Reefhuis, J., Rasmussen, S. A., Woomert, A., Hobbs, C., Romitti, P. A.

et al. Factors affecting maternal participation in the genetic component of the

National Birth Defects Prevention Study-United States, 1997-2007. Genet. Med. 16,

329-337 (2014).

28 The National Commission for the Protection of Human Subjects of Biomedical and

Behavioral Research. The Belmont Report: Ethical Principles and Guidelines for the

Protection of Human Subjects of Research. (1979).

http://www.hhs.gov/ohrp/humansubjects/guidance/belmont.html Accessed 22

November 2015.

29 Matsui, K. & Kita, Y. [Why do people consent to participate in genetic

epidemiological studies?] Nippon Koshu Eisei Zasshi 57, 977-987 (2010).

Table 1 Comparison of survey respondents to total participants

Age (years)<20 5 (0.2%) 32 (0.7%)20–29 665 (27.9%) 1,609 (35.4%)30–39 1,530 (64.1%) 2,654 (58.4%)≥40 176 (7.4%) 246 (5.4%)No answer 11 (0.5%) 0 (0%)

Birth month of childJul 2011–Jun 2012 680 (28.5%) 1,396 (30.7%)Jul 2012–Jun 2013 1,086 (45.5%) 2,214 (48.8%)Jul 2013–Jun 2014 600 (25.1%) 923 (20.3%)No answer 21 (0.9%) 8 (0.2%)

Residence at enrollmentChiba (Midori-ku) 382 (16.0%) 713 (15.7%)Kimitsu 1,133 (47.5%) 2,199 (48.4%)Awa 540 (22.6%) 998 (22.0%)Isumi 286 (12.0%) 527 (11.6%)Others, No Answer 46 (1.9%) 104 (2.3%)

a In the case of multiple participation, the first delivery date was used.

Survey respondents(N=2,358)

Total participants(N=4,541)

18

Figure 1 Motivation to participate in the study (N=2,358)

79

69

66

57

53

51

48

47

47

36

27

14

22

25

30

35

37

33

39

38

44

56

4

7

6

12

10

11

18

13

14

19

16

0% 50% 100%

Benefit my children or grandchildren

Monetary compensation

Contribute to making a better environment

Individual test results

Contribute to a successful study

Learn about children's growth

Gifts (goods)

Credibility of a national study

Helpful information for childrearing

Credibility of the research institute (university)

High quality of the research

Percent of respondents

Motivated Neither motivated nor unmotivated

Not motivated No answer

19

Figure 2 Participants' self-perceived understanding of studyaspects at the time of enrollment (N=2,358)

92

91

69

67

63

59

57

55

44

42

40

40

31

29

29

27

25

24

23

18

17

6

7

22

28

30

37

32

29

35

26

34

32

54

44

41

49

29

45

46

36

23

2

2

9

4

7

3

11

16

21

31

25

27

15

27

29

23

46

30

31

45

60

Voluntary nature of participation

No disadvantage for declining to participate

Confidentiality of personal information

Requirements for participation

Study duration

Study purpose

Withdrawal procedure

Data handling policy in case of withdrawal

Contact information for inquiries

Obtaining child's assent to participate in the future

Government ministry in charge of the JECS

Collecting medical records from hospital

Content to be analyzed

Monetary compensation

Amount of blood to be withdrawn

Requirements from 6 months after giving birth

Registration in the case of changing hospitals

Planned sample use for genetic analysis

Individual test results to be returned

Length of questionnaires

Inquiry of resident register in case of address unknown

Percent of respondents

Understood well Partially understood Not understood No answer

20

Figure 3 Participants' concerns about the study (N=2,358)

14

13

5

3

3

36

34

25

28

9

49

52

69

68

68

0% 50% 100%

Risk of personal information leakage

Burden of long-term commitment

Uncertainty about usefulness of study results

Skepticism about misuse of the data

Family opposition to participation

Percent of respondents

Concerned Neither concerned nor unconcerned

Not concerned No answer

21

Figure 4 Feature of respondents groups classified by motivation factors

Data are shown as standardized factor scores of motivation. Error bars indicate 95% confidence intervals.

-2

-1.5

-1

-0.5

0

0.5

1

1.5

High overall motivation

Not motivated by money or gifts

Motivated by money or gifts

Low overall motivation

Mea

n of

stan

dard

ized

fact

or sc

ores

of

mot

ivat

ion Contribution

Credibility

Helpful information

Money or gifts

22

Feature of group

p valuea p valuea p valuea

Number (%)

Age b

<30 29% <0.001 N.S. N.S.30–39 64%≧40 7%

Factor scores c

UnderstandingImplementation of the study 0.293 [ -0.358 , 1.003 ] -0.084 [ -0.765 , 0.577 ] <0.001 -0.174 [ -0.758 , 0.460 ] <0.001 -0.312 [ -0.927 , 0.388 ] <0.001Handling of personal data 0.331 [ -0.435 , 0.984 ] 0.037 [ -0.518 , 0.693 ] <0.01 -0.141 [ -0.677 , 0.526 ] <0.001 -0.261 [ -0.737 , 0.505 ] <0.001Voluntary nature 0.296 [ 0.230 , 0.334 ] 0.287 [ 0.228 , 0.335 ] N.S. 0.290 [ 0.206 , 0.338 ] N.S. 0.281 [ 0.185 , 0.329 ] <0.01Outline of the study 0.472 [ -0.275 , 0.789 ] 0.188 [ -0.402 , 0.673 ] <0.01 0.159 [ -0.553 , 0.668 ] <0.001 0.050 [ -0.792 , 0.617 ] <0.001Contact information 0.564 [ -0.503 , 0.892 ] 0.368 [ -0.602 , 0.769 ] <0.01 0.204 [ -0.686 , 0.718 ] <0.001 -0.034 [ -0.790 , 0.657 ] <0.001Data analysis -0.006 [ -0.297 , 1.147 ] -0.148 [ -0.475 , 0.823 ] <0.001 -0.212 [ -0.509 , 0.753 ] <0.001 -0.225 [ -0.511 , 0.748 ] <0.001

ConcernsRisks and benefits -0.651 [ -0.725 , -0.313 ] -0.482 [ -0.725 , 0.814 ] <0.001 -0.408 [ -0.651 , 0.983 ] <0.001 -0.239 [ -0.627 , 1.057 ] <0.001Mental burden -0.358 [ -0.768 , 0.101 ] -0.130 [ -0.768 , 0.512 ] <0.001 0.010 [ -0.449 , 0.561 ] <0.001 0.193 [ -0.449 , 0.561 ] <0.001

a P values for comparison with the "high overall motivation" group were calculated by chi-square test for age and Mann-Whitney U test for standarized factor scores, with Bonferroni correction.b Values represent percentage of respondents in groups.c Values represent median, 25th percentile and 75th percentile.

70%4%

329 (16%)

62%7%

26%32%

778 (37%)

Table 2 Comparison of groups classified by motivation with age, self-perceived understanding of study aspects, and concerns (N=2,106)

High overall motivation Not motivated bymoney or gifts

Motivated by money or gifts Low overall motivation

69%13%

674 (32%) 325 (15%)

19%

23

Factor 1 Factor 2 Factor 3 Factor 4

Credibility Helpfulinformation Money or gifts Contribution

Credibility of research institute (university) .89 -.04 -.02 -.06Credibility of a national study .82 -.11 .06 .03High quality of the research .46 .32 -.05 .08

Learn about children's growth -.04 .75 -.07 .00Helpful information for childrearing .00 .69 .05 .03Individual test results -.07 .67 .08 -.04

Monetary compensation -.04 -.07 1.03 .02Gifts (goods) .09 .21 .54 -.04

Contribute to making a better environment -.02 -.09 .00 .78Benefit my children or grandchildren -.05 .05 -.02 .63Contribute to a successful study .12 .07 .03 .40

Motivation factors and items

Supplementary Table 1 Results of maximum likelihood factor analysis for motivation toparticipate

Number represents factor loading of each item after promax rotation with Kaiser normalization. Factor loadings ≥0.35 are indicated in bold.

24

Factor 1 Factor 2 Factor 3 Factor 4 Factor 5 Factor 6Implementation

of the studyHandling of

personal dataVoluntary

natureOutline of the

studyContact

information Data analysis

Amount of blood to be withdrawn .77 -.03 .04 .04 -.07 -.05Length of questionnaires .74 .00 .01 -.04 -.05 -.03Requirements from 6 months after giving birth .55 -.06 -.04 .24 .02 .11Monetary compensation .48 .15 .03 -.04 .11 .04

Collecting medical records from hospital .00 .73 -.06 -.02 -.02 .01Data handling policy in case of withdrawal -.03 .67 .06 .11 -.06 -.06Confidentiality of personal information -.14 .51 .14 .17 -.02 .02Inquiry of resident register in case of address unknown .24 .48 -.10 -.17 .06 -.03Obtaining child's assent to participate in the future .05 .38 -.01 .02 .05 .02

No disadvantage for declining to participate .02 .01 .97 -.06 -.01 .00Voluntary nature of participation .02 -.04 .86 .01 .03 .00

Study duration .05 .01 -.07 .79 .05 -.11Study purpose -.14 .04 -.01 .56 -.02 .27Requirements for participation .23 .00 .08 .55 .01 -.03

Withdrawal procedure -.08 -.06 .01 .05 .93 -.02Contact information for inquiries .05 .11 .01 -.01 .59 .02

Content to be analyzed .01 -.04 .01 .03 -.02 .90Individual test results to be returned .27 .11 .00 -.09 .03 .44

Factors and items of self-perceived understanding

Supplementary Table 2 Results of maximum likelihood factor analysis for self-perceived understanding of study aspects

Number represents the factor loading of each item after promax rotation with Kaiser normalization. Factor loadings ≥0.35 are indicated in bold. Other items with factor loadings <0.35 are notshown.

25

Factor 1 Factor 2Risks andbenefits

Mentalburden

Skepticism about misuse of the data .97 -.12Risk of personal information leakage .59 .17

Uncertainty about usefulness of study results .36 .25

Burden of long-term commitment -.01 .57Family opposition to participation .06 .37

Supplementary Table 3 Results of maximum likelihood factoranalysis for concerns about the study

Factors and item of concerns

Number represents the factor loading of each item after promax rotation with Kaisernormalization. Factor loadings ≥0.35 are indicated in bold.

26

27

Supplementary File 1 Feedback questionnaire on participating in the Japan Environment & Child Study (JECS) at the Center of Chiba Unit

Date (yyyy/mm/dd) / / A) Personal information

1) Age

1□ 10—19 2□ 20—29 3□ 30—39 4□ 40—49

2) Birth month (or expected month of birth) of your child participating in the JECS (If you enrolled in the study more than once, please answer for each of your children.)

2011 1□ Jul—Sep 2□ Oct—Dec 2012 3□ Jan—Mar 4□ Apr—Jun 5□ Jul—Sep 6□ Oct—Dec 2013 7□ Jan—Mar 8□ Apr—Jun 9□ Jul—Sep 10□ Oct—Dec 2014 11□ Jan—Mar 12□ Apr—Jun

B) Information provided about the JECS (If you enrolled in the study more than once, please answer in relation to the information provided the first time.)

3) Did you know about the JECS before you received an explanation at a maternity hospital or local health center?

1□ Yes, I knew about it. → How did you know? 1-1□ Family/acquaintances

1-2□ Posters/flyers

1-3□ TV/radio

1-4□ Other ( )

2□ I had heard of it, but didn’t clearly understand what it was.

3□ I didn’t know about it.

4□ I don’t remember. 4) Where did you receive the maternity health record book?

1□ Midori-ku, Chiba 2□ Sodegaura 3□ Kisarazu 4□ Kimitsu 5□ Futtsu 6□ Kyonan

7□ Minamiboso 8□ Tateyama 9□ Kamogawa 10□ Katsuura 11□ Onjuku 12□ Isumi

13□ Otaki 14□ Ichinomiya 15□ Other city/town in Chiba Prefecture 16□ Outside of Chiba Prefecture 5) Did you receive an explanation about the JECS at the same time you received the maternity health record book?

1□ I received a full explanation.

2□ I received a partial explanation.

3□ I didn’t receive an explanation. → Why? 3-1□ Nobody was available to explain 3-2□ Not enough time to receive an explanation 3-3□ My family went to the local health center 3-4□ Other ( )

4□ I don’t remember.

28

6) At which hospital did you register to participate in the JECS?

1□ Kashiwagi Clinic 2□ Chiba Aoba Municipal Hospital 3□ Chiba University Hospital

4□ Mineta Maternity Clinic 5□ Miyake Women’s Clinic 6□ Muneta maternity Clinic

7□ Iijima Mother’s Clinic 8□ Yushudai Clinic 9□ Murata maternity Clinic 10□ Jujo Clinic

11□ Kato Hospital 12□ Koma Clinic 13□ Yakumaru Hospital 14□ Kimitsu Chuo Hospital

15□ Kumakiri Clinic 16□ Kiyokawa Clinic 17□ Famil Clinic 18□ Kameda Medical Center

19□ Ide Clinic 20□ Morikawa Clinic 21□ A hospital/clinic outside of Chiba Prefecture

7) Who explained the JECS to you?

1□ Medical doctor/nurse/midwife/hospital staff 2□ Staff from the Center of Chiba Unit

3□ Staff from the center of a different unit 4□ I don’t know

5□ I didn’t receive an explanation at a hospital

C) Decision to participate in the JECS (If you enrolled in the study more than once, please answer in relation to the first enrollment.)

8) Did you decide on your own to participate in the JECS?

1□ Yes (→Q9) 2□ Not sure 3□ No

↓ ↓ 8a) If you answered “Not sure” or “No”,

Who influenced your decision?

8-1□ Medical doctor/nurse/midwife/staff of hospital 8-2□ Staff from the Center of Chiba Unit

8-3□ Partner 8-4□ Parent 8-5□ Friend or acquaintance

8-6□ Other ( )

9) Did you understand everything you wanted to know about the study when you made the decision to

participate?

1□ No, I didn’t understand well. 2□ I partially understood. 3□ Yes, I understood well.

29

10) Did you understand the following items when you made the decision to participate? Please select your level of understanding from the choices below. Please check the box (right column) corresponding to any item for which you wanted a better explanation. When I made the decision to participate, I … I wanted to get

more information

1. didn’t understand well

2. partially understood

3. understood well

(Example) ○├ --------┼---------┤ ☑

Purpose of the study ├---------┼---------┤ □

Total duration of the study ├---------┼---------┤ □

Requirements for participation ├---------┼---------┤ □

Amount of blood sampling ├---------┼---------┤ □

Length of questionnaires ├---------┼---------┤ □

Requirements from 6 months after giving birth ├---------┼---------┤ □

Content to be analyzed from biological samples and questionnaires ├---------┼---------┤ □

Test results to be returned ├---------┼---------┤ □

Planned sample use for genetic analysis related to diseases and developmental disorders ├---------┼---------┤ □

Registration in the case of changing hospitals ├---------┼---------┤ □

Procedure for withdrawing from the study ├---------┼---------┤ □

Contact information for inquiries ├---------┼---------┤ □

Voluntary nature of participation in the study ├---------┼---------┤ □

Being at no disadvantage for declining to participate

├---------┼---------┤ □

Process of obtaining my child’s assent in the future ├---------┼---------┤ □

My name would not be disclosed to anyone other than institutions involved in JECS ├---------┼---------┤ □

Data would be used even if I withdrew from the study (unless I specifically asked for data to be destroyed)

├---------┼---------┤ □

Medical data would be collected from hospitals ├---------┼---------┤ □

Resident’s register would be accessed in the case my address was unknown ├---------┼---------┤ □

Monetary compensation would be paid ├---------┼---------┤ □

Name of the government ministry in charge of the JECS (Ministry of the Environment) ├---------┼---------┤ □

30

11) Were you concerned about any of the following when you made your decision to participate? Please select your level of concern for each of the items below. Please check the box (right column) corresponding to any item for which you still have concerns. 1. Not

concerned 2. Neither

concerned nor unconcerned

3. Concerned

Still have concerns

Burden of making a long-term commitment to the study ├---------┼---------┤ □

Family opposition to my participation ├---------┼---------┤ □

Risk of personal information leakage ├---------┼---------┤ □

Study results might not be useful ├---------┼---------┤ □

Study results might be misused ├---------┼---------┤ □

Effect of my lifestyle on my child ├---------┼---------┤ □

Effect of my eating habits on my child ├---------┼---------┤ □

Effect of living environment on my child ├---------┼---------┤ □

My child’s growth ├---------┼---------┤ □

12) Were you motivated to participate in the JECS by any of the following when you made your decision to participate? Please select your level of motivation for each of the items listed below. Please check the box (right column) corresponding to a reason for why you are continuing to participate.

1. Not motivated

2. Neither motivated nor not motivated

3. Motivated Reason for continuing

participation

Contribute to making a better environment ├---------┼---------┤ □

Benefit my children or grandchildren ├---------┼---------┤ □

Contribute to a successful study ├---------┼---------┤ □

Credibility of the hospital ├---------┼---------┤ □

Credibility of the municipal government ├---------┼---------┤ □

Credibility of Chiba University ├---------┼---------┤ □

Credibility of the national study ├---------┼---------┤ □

High quality of the research study ├---------┼---------┤ □

Learn about children’s growth ├---------┼---------┤ □

Individual test results ├---------┼---------┤ □

Helpful information for childrearing ├---------┼---------┤ □

Monetary compensation ├---------┼---------┤ □

Gifts (goods) ├---------┼---------┤ □

31

D) After enrolling in the JECS

13) Did you feel that any of the following were burdensome? Please select the level of burden for each of the items listed below. Please check the box (right column) corresponding to any item that you have not done and so cannot answer.

1. Not burdensome

2. A little burdensome

3. Very burdensome Can’t answer because I haven’t done it

Questionnaire (mid- to late pregnancy at the time of enrollment)

├-------------┼-------------┤ □

Questionnaire (1–6 months after childbirth) ├-------------┼-------------┤ □

Questionnaire (1–1.5 years after childbirth) ├-------------┼-------------┤ □

Blood drawing ├-------------┼-------------┤ □

Urine collection ├-------------┼-------------┤ □

Hair collection ├-------------┼-------------┤ □

Breast milk collection ├-------------┼-------------┤ □

Other burdens, if any

14) How do you feel about the following? Please select your level of agreement with the items listed below.

1. Disagree 2. Neither agree nor disagree

3. Agree

My participation will benefit children ├--------------┼--------------┤

I am contributing to society ├--------------┼--------------┤

I could look into my daily life ├--------------┼--------------┤

I became more interested in the environment ├--------------┼--------------┤

I could get helpful information on childrearing. ├--------------┼--------------┤

It became easy to ask others about childrearing. ├--------------┼--------------┤

Other positive aspects, if any

32

E) Suggestions, comments, and requests

15) Do you have any suggestions about content you would like to see in newsletters?

16) Are there any topics you would like to learn about in the participants’ lecture meetings?

17) Do you have any requests for events other than lecture meetings?

18) If you have any other comments, please let us know in the space below.

Thank you for your cooperation with our questionnaire.

Journal of Human Genetics

平成 27 年 12 月 投稿中